This invention relates to improvements in techniques for destroying cells within the living body and, more particularly, to apparatus and a method for applying electromagnetic energy to the interior of a tumor within the body to destroy cells in the tumor.
Hyperthermia, the heating of the body cells to above 41.degree. C. for therapeutic purposes, particularly to destroy cancer tumors, has been known and used in the past. It is also known, that, above 46.degree. C., irreversible destruction of healthy and diseased body cells occurs. The purpose of hyperthermia equipment generally is to deliver heat preferentially to diseased body cells while maintaining adjacent healthy cells at acceptable temperatures, i.e., below the temperature at which irreversible cell destruction occurs.
There are three main theories which explain why hyperthermia is successful in fighting cancerous growths. Some scientists believe that heat produces a localized fever which causes lymphocytes to congregate (200 lymphocytes are usually needed to destroy one cancerous cell). Other scientists think heat improves the flow of blood in the tumor, and this increased blood flow, in turn, brings more oxygen to the tumor and lowers its PH, thus starving the tumor cells by reducing nutrients. A third theory contends that the DNA forces that hold tumorous cells together are weaker than those of healthy cells and the heat applied to the tumorous cells breaks them apart and thereby destroys them more easily.
A number of disclosures relating to the method of treating tumors by the application of electromagnetic radiation to the tumors include U.S. Pat. Nos. 3,991,770, 4,032,860, 4,095,602, 4,119,102, 4,154,246, 4,230,129, 4,346,715 and 4,397,314. Another disclosure relating to surgical instruments in the form of an electrically heated hypodermic needle is U.S. Pat. No. 3,698,394.
A commercial system for producing deep controlled regional hyperthermia has been made and sold by BSD Medical Corporation, 420 Chipeta Way, Salt Lake City, Utah 84108. The system uses the principle of phase reinforcement to create an electrical field within the human body that produces heat internally. A number of radiating elements surround the patient and direct radio frequency (RF) energy through the treatment area in the applicator field. Thus, the sources of electromagnetic energy for the area to be treated in the patient are external to the patient.
A technique of treating brain tumors by microwave energy has been disclosed in an article entitled, "Brain Tumors Succumb to New Microwave Probes," in Microwave Technology, June 19, 1983. In this technique, a hole is drilled into the skull and a catheter is invasively inserted in the hole to support a coaxial radiator or antenna. Microwave energy is then applied to the antenna to cause the brain tumor to be heated to the point at which cancerous cells in the tumor are destroyed.
The foregoing disclosures relate to hyperthermia equipment which is complex in construction, expensive to produce and maintain, and requires a considerable volume of space to accommodate the relatively large size of such equipment. Because of these drawbacks, a need has arisen for improved hyperthermia equipment and techniques which simplifies the way internal body tumors are treated, for example, tumors of the breast. The present invention satisfies this need.